6-pin PCIe to 4-pin Molex

So I have some proprietary PCIe x1 add-in cards for communicating with a microscope. They require auxiliary power through a female 4-pin molex receptacle on the cards. My Dell OEM PSU only has two spare 6-pin cables. No molex at all. I have some adapters for molex to 6-pin, that is, two female molex and making one male 6-pin, for systems that lack a 6-pin for graphics cards. I need the opposite. One 6-pin female to two molex male. I cannot find this anywhere. Is there a reason for it? Is that not technically feasible? I was just going to make one by switching around the connectors. Is this a bad idea?